In tungsten inert gas welding torches, an arc burns between a non-consuming tungsten electrode and a workpiece. The electrode is usually connected as a cathode. Since the emission of electrons as free charge carriers is achieved mainly by high temperatures, it is desired to achieve high power densities in the electrode. This can be achieved by a conical cone-shaped form of the tungsten electrode. It is also desired that the starting point of the arc lies as close as possible in the direction of the workpiece, which is assisted by the conical form of the electrode tip. For the high temperatures occurring at the electrode, cooling is required, in order to prevent or at least limit its wear.
Usually, an inert gas is passed through the torch in the direction of the workpiece. For this there is an inert gas nozzle. This nozzle allows the inert gas to be formed as a closed veil around the arc. The inert gas nozzle thereby encloses the electrode and is arranged alongside it.
DE 10 2009 008 250 A1 discloses a torch for tungsten inert gas welding in which an electrode unit is held in a housing made of a metal by means of an electrode holder. For cooling the electrode unit, there is a cooling device, by which liquid cooling medium can be conducted into the electrode holder and out of it again. For this purpose, in the electrode holder there is formed a cavity, in which the cooling medium can be conducted into this cavity and out of it again via a cooling tube. After leaving the cooling tube, the cooling medium can impinge directly on the end face of the electrode unit. In this way, direct cooling of the electrode unit is achieved.